Underground Services and Trees

[LX-Markham]

Hi,
New guy here. Wiring up my garage renovation this week and have a question I couldn't find in my search.

Installing a new 200A box in the house and running a new line out to the garage to install a 100A box to feed:

• 4-post car lift
• roll-up garage door
• compressor
• welder
• general lighting and outlets

Dug a trench from the corner of the house where the existing electrical panel is in the basement, to the corner of the garage where the new sub-panel is going to be installed.

Took all weekend, it was tough sleddin' through the hard clay. Anyway, afterwards, I asked our landscape architect if he wanted me to tee a waterline off for the new water feature (we're having the back yard landscaped next month). He pointed out that he was planning putting a nice tree right where I put the trench (about 2/3 the way to the corner of the garage).

So the question is: will the tree roots bother the electrical line?

I'm also planning on running a poly pipe water line and a gas line in the trench. The trench is 2' deep.

The tree is a Japanese Tree Lilac. Supposedly has a 'shallow' root ball.

Any suggestions (other than relocating the trench) are welcome
We're also looking at relocating the tree, but honestly it's the perfect location for it (privacy screening).

 

[Aceman]

I take it you've seen what tree roots do to pavement and sidewalks when they are planted right next to them? There is no way I'd recommend planting a tree over a conduit.

There is also the potential for the conduit to get torn up if someone ever tried to dig up the tree or if it blew over in a few years with the roots wrapped around the conduit.

 

[Full Size 66]

I feel uniquely qualified to respond as I own a tree company. I do work for many customers who have me remove trees encroaching on utilities. The usual is water or sewer. The problem with electrical is when you go for removal of the cute little tree that has grown out of control. To do a proper stump grind you should go 1.5-2 feet deep. This is only one example of why not. I think it is a bad idea.

 

[G_P]

No way I would plant a tree over utilities. Shallow roots or not they will go over 2' deep.

Put the tree elsewhere if you really want it. Leave the utility path clear for future service and for peace of mind that some random storm wont tear up all your wires and pipes.

 

[jabberwoki]

Can you provide the correct botanical name for the tree? if it`s a small tree or tall shrub it should not be a problem all depends in the species.
You can also consider a root barrier.

 

[where2]

Start with the number one, since you have one nice existing trench.
Ask yourself how many times you want to re-dig that trench?
Add one for each time you plant a tree over your wire duct.
What's the sum of the above equation? Is the answer greater than the number of times you want to dig the trench? If yes, move tree.

So, from where you are now, your options are move the trench, move the tree, or dig deeper. If you decide to dig deeper and find yourself asking the question "How much deeper?" Repeat the equation above...

 

[CNGsaves]

Consider planting that particular small ornamental tree in a big container that is partially dug into the ground just outside the trenchline.

Planting any tree with long taproot right over top of trench-line is just asking for trouble as that replaced soil will be looser than surrounding soil and roots will go crazy in that space!! That would NOT be good long-term.

 

[LX-Markham]

Thanks for the responses. Not what I wanted to hear, but it confirms my initial gut feel.

I considered using PVC conduit to 'sleeve' under the root ball and some kind of root barrier.

Can you provide the correct botanical name for the tree? if it`s a small tree or tall shrub it should not be a problem all depends in the species.
You can also consider a root barrier.

Syringa reticulata cvs.
Japanese Tree Lilac cultivars

 

[Tscott]

Why not just run the whole thing in PVC. While your at it throw in a few extras for good measure so you never have to dig that trench again. Lay the PVC out so that there is no glue joint under the root area of the tree. Roots cannot grow through PVC unless they have a way in.

Tom

 

[SwerveDriver]

X2 for the PVC idea. ^^ I am uncertain as to any ramifications of placing an electric service, gas line and water line in the same ditch- or pipe run.
SD

 

[LX-Markham]

^^^I looked that up, and nothing said I couldn't. Minimum depth for electrical and gas are satisfied, and as for the water not being below frost I'm just going to blow the lines out every fall. Just need water during the summer to wash the car

 

[pattenp]

Since you're in Canada are you using something similar to Southwire ACWU 90 direct bury armored cable for the power feed? Looking at the stone in your trench you need the armored cable or use PVC conduit.

 

[LX-Markham]

I'm going to PVC conduit. It's only a 26' run from corner to corner.

And those aren't stones, they are lumps of hard clay!

 

[pattenp]

Okay. I thought I was seeing some gravel in the bottom of the trench.

I'm going to PVC conduit. It's only a 26' run from corner to corner.

And those aren't stones, they are lumps of hard clay!